The present invention relates to an endoscope, and more particularly, to an endoscope having a treatment instrument direction setting table for setting a direction in which a tip of the treatment instrument protruded from a distal end of an insertion section of the endoscope.
Generally, in side-view type endoscopes, a treatment instrument direction setting table is provided. The treatment instrument direction setting table (which will be referred to as a direction setting table hereinafter) is provided at a distal end portion of an insertion section of the endoscope. The direction setting table is used for varying a direction in which the tip end of the treatment instrument, which is inserted through an instrument-inserting channel formed through the endoscope, protrudes from the distal end portion of the insertion section. The direction set by the direction setting table can be varied, generally, by operating an operation member provided at an operation unit, which is connected to the proximal end of the insertion section. Upon operation of the operation member, an operation wire connecting the operation member and the direction setting table is operated and the direction of the direction setting table can be changed remotely.
In the endoscope having the structure as described above, if a treatment instrument, through which a high frequency current flows, is used, and if the high frequency current leaks onto the direction setting table, it may flow in the operation unit. In such a case, an operator of the endoscope may suffer burns when he/she touches metallic members such as an operation lever provided at the operation unit.
In order to avoid such a problem, in conventional endoscopes, the surface of the direction setting table and/or the surface of members which contact the direction setting table are formed of electrically insulating material. Examples of such configurations are described in Japan Utility Model Provisional Publications No. SHO 57-60601 and No. SHO 62-90602.
However, with such a structure, the direction setting table and/or the member contacting the direction setting table may not have sufficient mechanical strength and easily break and/or may require complicated manufacturing processes. Accordingly, such a structure is not suitable for practical use.
It is therefore an object of the invention to provide an improved endoscope, with which the above problem of burns due to the leakage of the high frequency current can be prevented with a structure suitable for practical use.
For the above object, according to the invention, there is provided an endoscope, which is provided with an operation unit provided with at least one operation member, an insertion section to be inserted in a human cavity, the operation unit being connected with a proximal end of the insertion section, a direction setting table provided at a distal end portion of the insertion section, the direction setting table adjusting a direction in which a distal end of a treatment instrument inserted through an instrument-inserting channel protrudes from a distal end portion of the insertion section of the endoscope, and an operation wire that moves along the axis thereof upon operation of the operation member, the operation wire being connected to the direction setting table so that the direction setting table is moved in accordance with operation of the operation member. With this structure, the distal end portion of the insertion section and the operation unit is electrically insulated.
Since the distal end portion of the insertion section is electrically insulated with respect to the operation unit, even if the electrical current leaks to a metallic member at the distal end portion of the insertion section, the electrical current never flows in the operation unit, and the operator will not suffer burns or the like.
In a particular case, the direction setting table is made of metal. Even in this case, the electrical current does not flow in the operation unit.
Optionally, the direction setting table may be held by a body member, which is made of metal, provided at the distal end portion of the insertion section, and the body member may be connected with the insertion section. In this structure, body member can be electrically isolated from members of the insertion section.
Still optionally, the operation wire is surrounded by electrically insulating material, and the operation wire is electrically insulated with respect to the operation member of the operation unit.
Further optionally, the operation wire is connected to the operation member via a link mechanism, the link mechanism including a link member connected to the operation member, and a rod member connecting the link member and the operation wire, the rod member being fitted in and guided by a tube member so as to move in an axial direction thereof.
With this structure, the tube member may be formed of insulating material.
Further, in this structure, a proximal end of the wire is secured to the rod member, the rod member being made of insulating material.
Furthermore, an O-ring is provided on the rod member, the O-ring being deformed to have an elliptic shape, a rotational movement of the rod member with respect to the tube member being prevented due to the elliptic shape of the O-ring.